Background Anxiety and trauma spectrum disorders are highly prevalent among Veterans from all war eras, causing significant impairment in social and occupational functioning and poor quality of life across the lifespan. Posttraumatic stress disorder, panic, social anxiety, and generalized anxiety disorders are associated with substantial decrements in health, quality of life, interpersonal and vocational functioning. Many Veterans with mental health concerns report experiencing difficulty in social functioning, productivity, community involvement, and self-care. Although cognitive behavioral therapy (CBT) for anxiety-based disorders is highly effective, conventional CBT formats require 3 to 4 months to complete, which is often a barrier for Veterans because it requires substantial time away from work, school, and other important life activities. Thus, relatively few Veterans undergo and complete treatment. Preliminary data support the feasibility, effectiveness, and acceptability of an intensive weekend treatment delivery format and show improvement in functional and clinical outcomes. Objectives The current project proposes to evaluate a brief but intensive transdiagnostic CBT that simultaneously targets multiple anxiety disorders with or without co-occurring depression. This will be accomplished by evaluating an innovative treatment delivery method that directly addresses barriers associated with standard psychotherapy delivery. The main objectives are to (1) determine if an intensive CBT protocol (iCBT) delivered over one weekend can improve community reintegration, quality of life, and emotional functioning compared with standard CBT (sCBT) and treatment as usual (TAU); (2) examine the rates of psychotherapy engagement in iCBT compared with sCBT; and (3) obtain a deeper understanding, through qualitative interviews with Veterans and their family members, of how iCBT and environmental factors may impact the process of reintegration and quality of life. Methods The proposed study is a randomized controlled trial with 3 treatment arms. A transdiagnostic group CBT protocol will be compared in a compressed weekend format (iCBT) with a standard group delivery format involving 3 months of weekly sessions (sCBT). A treatment as usual (TAU) condition will be included to compare outcomes. Veterans with one or more anxiety- based disorder(s) (with or without co-occurring depression) will be randomized to one of the three treatment arms. Veterans will be asked to attend a total of four assessments during the study including a baseline evaluation, 1-month, 3-month, and 6-month follow-ups. Qualitative interviews will be conducted with Veterans who completed iCBT and family members.